#!/usr/bin/env python3
#
# backport-create-issue
#
# Standalone version of the "backport-create-issue" subcommand of
# "ceph-workbench" by Loic Dachary.
#
# This script scans Redmine (tracker.ceph.com) for issues in "Pending Backport"
# status and creates backport issues for them, based on the contents of the
# "Backport" field while trying to avoid creating duplicate backport issues.
#
# Copyright (C) 2015 <contact@redhat.com>
# Copyright (C) 2018, SUSE LLC
#
# Author: Loic Dachary <loic@dachary.org>
# Author: Nathan Cutler <ncutler@suse.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see http://www.gnu.org/licenses/>
#
import argparse
import logging
import os
import re
import time
from redminelib import Redmine  # https://pypi.org/project/python-redmine/

redmine_endpoint = "https://tracker.ceph.com"
project_name = "Ceph"
release_id = 16
delay_seconds = 5
redmine_key_file="~/.redmine_key"
#
# NOTE: release_id is hard-coded because
# http://www.redmine.org/projects/redmine/wiki/Rest_CustomFields
# requires administrative permissions. If and when
# https://www.redmine.org/issues/18875
# is resolved, it could maybe be replaced by the following code:
#
# for field in redmine.custom_field.all():
#     if field.name == 'Release':
#         release_id = field.id
#
status2status_id = {}
project_id2project = {}
tracker2tracker_id = {}
version2version_id = {}
resolve_parent = None

def usage():
    logging.error("Redmine credentials are required to perform this operation. "
                  "Please provide either a Redmine key (via %s) "
                  "or a Redmine username and password (via --user and --password). "
                  "Optionally, one or more issue numbers can be given via positional "
                  "argument(s). In the absence of positional arguments, the script "
                  "will loop through all issues in Pending Backport status." % redmine_key_file)
    exit(-1)

def parse_arguments():
    parser = argparse.ArgumentParser()
    parser.add_argument("issue_numbers", nargs='*', help="Issue number")
    parser.add_argument("--user", help="Redmine user")
    parser.add_argument("--password", help="Redmine password")
    parser.add_argument("--resolve-parent", help="Resolve parent issue if all backports resolved/rejected",
                        action="store_true")
    parser.add_argument("--debug", help="Show debug-level messages",
                        action="store_true")
    parser.add_argument("--dry-run", help="Do not write anything to Redmine",
                        action="store_true")
    parser.add_argument("--force", help="Create backport issues even if status not Pending Backport",
                        action="store_true")
    return parser.parse_args()

def set_logging_level(a):
    if a.debug:
        logging.basicConfig(level=logging.DEBUG)
    else:
        logging.basicConfig(level=logging.INFO)
    return None

def report_dry_run(a):
    if a.dry_run:
        logging.info("Dry run: nothing will be written to Redmine")
    else:
        logging.warning("Missing issues will be created in Backport tracker "
                         "of the relevant Redmine project")

def process_resolve_parent_option(a):
    global resolve_parent
    resolve_parent = a.resolve_parent
    if a.resolve_parent:
        logging.warning("Parent issues with all backports resolved/rejected will be marked Resolved")

def connect_to_redmine(a):
    full_path=os.path.expanduser(redmine_key_file)
    redmine_key=''
    try:
        with open(full_path, "r") as f:
            redmine_key = f.read().strip()
    except FileNotFoundError:
        pass

    if a.user and a.password:
        logging.info("Redmine username and password were provided; using them")
        return Redmine(redmine_endpoint, username=a.user, password=a.password)
    elif redmine_key:
        logging.info("Redmine key was read from '%s'; using it" % redmine_key_file)
        return Redmine(redmine_endpoint, key=redmine_key)
    else:
        usage()

def releases():
    return ('argonaut', 'bobtail', 'cuttlefish', 'dumpling', 'emperor',
            'firefly', 'giant', 'hammer', 'infernalis', 'jewel', 'kraken',
            'luminous', 'mimic', 'nautilus', 'octopus')

def populate_status_dict(r):
    for status in r.issue_status.all():
        status2status_id[status.name] = status.id
    logging.debug("Statuses {}".format(status2status_id))
    return None

# not used currently, but might be useful
def populate_version_dict(r, p_id):
    versions = r.version.filter(project_id=p_id)
    for version in versions:
        version2version_id[version.name] = version.id
    #logging.debug("Versions {}".format(version2version_id))
    return None

def populate_tracker_dict(r):
    for tracker in r.tracker.all():
        tracker2tracker_id[tracker.name] = tracker.id
    logging.debug("Trackers {}".format(tracker2tracker_id))
    return None

def has_tracker(r, p_id, tracker_name):
    for tracker in get_project(r, p_id).trackers:
        if tracker['name'] == tracker_name:
            return True
    return False

def get_project(r, p_id):
    if p_id not in project_id2project:
        p_obj = r.project.get(p_id, include='trackers')
        project_id2project[p_id] = p_obj
    return project_id2project[p_id]

def url(issue):
    return redmine_endpoint + "/issues/" + str(issue['id'])

def set_backport(issue):
    for field in issue['custom_fields']:
        if field['name'] == 'Backport' and field['value'] != 0:
            issue['backports'] = set(re.findall('\w+', field['value']))
            logging.debug("backports for " + str(issue['id']) +
                          " is " + str(field['value']) + " " +
                          str(issue['backports']))
            return True
    return False

def get_release(issue):
    for field in issue.custom_fields:
        if field['name'] == 'Release':
            return field['value']

def update_relations(r, issue, dry_run):
    global resolve_parent
    relations = r.issue_relation.filter(issue_id=issue['id'])
    existing_backports = set()
    existing_backports_dict = {}
    for relation in relations:
        other = r.issue.get(relation['issue_to_id'])
        if other['tracker']['name'] != 'Backport':
            logging.debug(url(issue) + " ignore relation to " +
                url(other) + " because it is not in the Backport " +
                "tracker")
            continue
        if relation['relation_type'] != 'copied_to':
            logging.error(url(issue) + " unexpected relation '" +
                relation['relation_type'] + "' to " + url(other))
            continue
        release = get_release(other)
        if release in existing_backports:
            logging.error(url(issue) + " duplicate " + release +
                          " backport issue detected")
            continue
        existing_backports.add(release)
        existing_backports_dict[release] = relation['issue_to_id']
        logging.debug(url(issue) + " backport to " + release + " is " +
            redmine_endpoint + "/issues/" + str(relation['issue_to_id']))
    if existing_backports == issue['backports']:
        logging.debug(url(issue) + " has all the required backport issues")
        if resolve_parent:
            maybe_resolve(issue, existing_backports_dict, dry_run)
        return None
    if existing_backports.issuperset(issue['backports']):
        logging.error(url(issue) + " has more backport issues (" +
            ",".join(sorted(existing_backports)) + ") than expected (" +
            ",".join(sorted(issue['backports'])) + ")")
        return None
    backport_tracker_id = tracker2tracker_id['Backport']
    for release in issue['backports'] - existing_backports:
        if release not in releases():
            logging.error(url(issue) + " requires backport to " +
                "unknown release " + release)
            break
        subject = (release + ": " + issue['subject'])[:255]
        if dry_run:
            logging.info(url(issue) + " add backport to " + release)
            continue
        other = r.issue.create(project_id=issue['project']['id'],
                               tracker_id=backport_tracker_id,
                               subject=subject,
                               priority='Normal',
                               target_version=None,
                               custom_fields=[{
                                   "id": release_id,
                                   "value": release,
                               }])
        logging.debug("Rate-limiting to avoid seeming like a spammer")
        time.sleep(delay_seconds)
        r.issue_relation.create(issue_id=issue['id'],
                                issue_to_id=other['id'],
                                relation_type='copied_to')
        logging.info(url(issue) + " added backport to " +
                     release + " " + url(other))
    return None

def maybe_resolve(issue, backports, dry_run):
    '''
    issue is a parent issue in Pending Backports status, and backports is a dict
    like, e.g., { "luminous": 25345, "mimic": 32134 }.
    If all the backport issues are Resolved/Rejected, set the parent issue to Resolved, too.
    '''
    global delay_seconds
    global redmine
    global status2status_id
    if not backports:
        return None
    pending_backport_status_id = status2status_id["Pending Backport"]
    resolved_status_id = status2status_id["Resolved"]
    rejected_status_id = status2status_id["Rejected"]
    logging.debug("entering maybe_resolve with parent issue ->{}<- backports ->{}<-"
                  .format(issue.id, backports))
    assert issue.status.id == pending_backport_status_id, \
        "Parent Redmine issue ->{}<- has status ->{}<- (expected Pending Backport)".format(issue.id, issue.status)
    all_resolved = True
    resolved_equiv_statuses = [resolved_status_id, rejected_status_id]
    for backport in backports.keys():
        tracker_issue_id = backports[backport]
        backport_issue = redmine.issue.get(tracker_issue_id)
        logging.debug("{} backport is in status {}".format(backport, backport_issue.status.name))
        if backport_issue.status.id not in resolved_equiv_statuses:
            all_resolved = False
            break
    if all_resolved:
        logging.debug("Parent ->{}<- all backport issues in status Resolved".format(url(issue)))
        note = ("While running with --resolve-parent, the script \"backport-create-issue\" "
                "noticed that all backports of this issue are in status \"Resolved\" or \"Rejected\".")
        if dry_run:
            logging.info("Set status of parent ->{}<- to Resolved".format(url(issue)))
        else:
            redmine.issue.update(issue.id, status_id=resolved_status_id, notes=note)
            logging.info("Parent ->{}<- status changed from Pending Backport to Resolved".format(url(issue)))
            logging.debug("Rate-limiting to avoid seeming like a spammer")
            time.sleep(delay_seconds)
    else:
        logging.debug("Some backport issues are still unresolved: leaving parent issue open")

def iterate_over_backports(r, issues, dry_run=False):
    counter = 0
    for issue in issues:
        counter += 1
        logging.debug("{} ({}) {}".format(issue.id, issue.project,
            issue.subject))
        print('Examining issue#{} ({}/{})\r'.format(issue.id, counter, len(issues)), end='', flush=True)
        if not has_tracker(r, issue['project']['id'], 'Backport'):
            logging.info("{} skipped because the project {} does not "
                "have a Backport tracker".format(url(issue),
                issue['project']['name']))
            continue
        if not set_backport(issue):
            logging.error(url(issue) + " no backport field")
            continue
        if len(issue['backports']) == 0:
            logging.error(url(issue) + " the backport field is empty")
        update_relations(r, issue, dry_run)
    print('                                     \r', end='', flush=True)
    logging.info("Processed {} issues".format(counter))
    return None


if __name__ == '__main__':
    args = parse_arguments()
    set_logging_level(args)
    process_resolve_parent_option(args)
    report_dry_run(args)
    redmine = connect_to_redmine(args)
    project = redmine.project.get(project_name)
    ceph_project_id = project.id
    logging.debug("Project {} has ID {}".format(project_name, ceph_project_id))
    populate_status_dict(redmine)
    pending_backport_status_id = status2status_id["Pending Backport"]
    logging.debug("Pending Backport status has ID {}"
        .format(pending_backport_status_id))
    populate_tracker_dict(redmine)
    force_create = False
    if args.issue_numbers:
        issue_list = ','.join(args.issue_numbers)
        logging.info("Processing issue list ->{}<-".format(issue_list))
        if args.force:
            force_create = True
            logging.warn("--force option was given: ignoring issue status!")
            issues = redmine.issue.filter(project_id=ceph_project_id,
                                          issue_id=issue_list)

        else:
            issues = redmine.issue.filter(project_id=ceph_project_id,
                                          issue_id=issue_list,
                                          status_id=pending_backport_status_id)
    else:
        if args.force:
            logging.warn("ignoring --force option, which can only be used with an explicit issue list")
        issues = redmine.issue.filter(project_id=ceph_project_id,
                                      status_id=pending_backport_status_id)
    if force_create:
        logging.info("Processing {} issues regardless of status"
                     .format(len(issues)))
    else:
        logging.info("Processing {} issues with status Pending Backport"
                     .format(len(issues)))
    iterate_over_backports(redmine, issues, dry_run=args.dry_run)
